Yes it was just in reference that their opposite from their parents & family.
Juhyeok mom is an alpha and the whole family are alphas but he is the opposite he's an omega a recessive one.
Su-ah Dad is an omega and his family is made up of omegas but he is the opposite his an alpha a dominant one.
So both kids are a 1st in the family & neither parent had a clue on how to deal with it.. hope this helps.
Secondary genders is the omegaverse, you could think of alpha as the “male” (can impregnate) and the omega as “female” (the one who can get pregnant) and beta is like the normal or primary gender (like us). Fun fact In omegaverse alpha x omega is considered as straight, even when they’re malexmale or femalexfemale :) So when they said in the beginning about raising opposite secondary genders, they just basically meant raising an alpha and an omega.

What does opposite secondary genders mean? They say it in the beginning. Is it that they are opposite genders from their parents?